北京地区SO2、NOx、O3和PM2.5变化特征的城郊对比分析

2006-01-01～2006-12-31在北京上甸子区域大气本底站和城区宝联环境观测站连续观测了SO2、NOx、O3和PM2.5的浓度,分析了北京城区和郊区的季节变化及日变化的差异,并结合风向讨论了城区污染对于大气本底的影响.结果表明,①NOx、SO2浓度在采暖季城郊差异最大,城区是本底的4～6倍,城郊O3有一致的浓度变化.本底站PM2.5在4、5月达到100μg/m3以上,是年平均的2～3倍;②NOx和SO2的日变化在城区表现为双峰型,在09:00前后和22:00前后形成高值,郊区表现为单峰型,在22:00前后出现高值.郊区O3的日变化峰值滞后于城区大约2 h.PM2.5日变化规律表现得较不规则;③西南风条件下本底各污染物浓度明显受城区输送影响而升高,东北风条件下干洁气团的影响比较明显.

Comparison analysis of variation characteristics of SO2, NOx, O3 and PM2.5 between rural and urban areas, Beijing

The concentrations of SO2, NOx, O3 and PM2.5 were observed continuously at Shangdianzi atmospheric background monitoring station and Baolian urban environmental monitoring station from 2006-01-01 to 2006-12-31. The difference of seasonal variation and diurnal variation between rural and urban areas was analyzed. And the relationship between wind direction and pollutant concentration at background station was discussed. The results showed that. 1) The difference of NOx and SO2 concentrations between rural and urban was most prominent in winter. The concentrations in urban had 4-6 times more than that in rural. The variation trends of O3 were similar in urban and rural. PM2.5 was more than 100 microg/m3 in April and May in rural, which was 2-3 times more than annually average. 2) The diurnal variation of NOx and SO2 showed two peaks, one around 09:00 and the other around 22:00. That showed one peak around 22:00 in rural. The rural ozone daily peak was 2 h later than the urban. The diurnal variation of PM2.5 was not regular. 3) The pollutant concentrations seemed obviously high when southwest wind prevailed and brought the polluted air from urban. Contrarily, that was very low when northeast wind prevailed and brought the clean air.